1. Field of the Invention
The present invention relates to an inkjet printer, and specifically relates to an inkjet printer which employs an ink circulation system and has a function of adjusting the temperature of ink circulating therein.
2. Description of the Related Art
Low-cost inkjet printers which are capable of high-speed color printing are widely used. An inkjet printer is connected to a terminal, such as a personal computer, and then takes in data of image, such as letters, illustrations and symbols, produced by the terminal, and prints the image on a sheet. With a multifunctional inkjet printer integrated with a scanner and a facsimile, image data taken in from the scanner unit or image data transferred through the facsimile can be printed.
In an inkjet printer, a temperature range which guarantees the performance of ink used for printing is specified in order to obtain a good print result. Japanese Unexamined Patent Application Publication No. 2006-88575 discloses an inkjet printer employing an ink circulation system which is configured to circulate ink therein, and is effective in guaranteeing the performance of the ink as described above. This inkjet printer includes a heater which is configured to heat the ink, and a cooler which is configured to cool the ink. When the temperature of the ink is too low to be in the temperature range which guarantees the performance of the ink, the ink is heated by using the heater. When the temperature of the ink is too high to be in the temperature range which guarantees the performance of the ink, the ink is cooled by using the cooler. The heater and the cooler are provided along an ink circulation path with the ink circulation path in between so as to make an ink circulation unit thereof smaller.
In an inkjet printer employing this type of ink circulation system, however, even if the ink flowing in the ink circulation path is heated by using the heater, the cooler which is provided side by side with the heater ends up drawing the heat from the ink. Accordingly, with poor heating efficiency as a result, it is necessary to increase heat energy from the heater in order to guarantee the performance of the ink. This leads to an increase in power consumption of the inkjet printer.
Japanese Unexamined Patent Application Publication No. 2009-255327 discloses a printing device which solves such a technical problem. This printing device includes in an ink circulation path thereof: a heater-side path which goes through a heater; a cooler-side path which goes through a cooler; a solenoid valve which is configured to switch back and forth between the heater-side path and the cooler-side path; and a controller which is configured to control the solenoid valve by software processing. The solenoid valve is driven by control coming from the controller, so that the flow of ink into the heater-side path and the flow of ink into the cooler-side path can be switched back and forth therebetween. In other words, in this printing device, it is possible to efficiently heat the ink flowing in the heater-side path by using the heater, or efficiently cool the ink flowing in the cooler-side path by using the cooler by switching the path by the solenoid valve.